Pilot light



Patented Apr. 9, 1940 UNl'lE-D STATES PATENT pr nce This invention relates in general to a pilotlight shunting a circuit which is opened and closed for turning on an electrical load, and is more particularly described in connection with an electrical switch in which the pilot light would be illuminated when the switch is open and will be extinguished when the switch is closed.

One of the principal objects of this invention is in the provision of a pilot light switch in which the light will be automatically illuminated when the switch is turned off so that the latter may be more readily found in the dark.

An important object of the invention is in the provision of a pilot light of the gas filled or neon type which has very high or substantially infinite resistance when cold, and which has a definite potential flash point and a very low current consumption when it is lighted.

A further object of the invention is in the pro- Vision of a pilot lamp which is incorporated as a part of an ordinary switch without changing anyexisting wiring installation but simply providing a lamp opening in the switch plate and inserting a lamp in the switch box below the plate connected in shunt with the switch to the circuit controlled by the switch.

Other and further objects of the invention will appear hereinafter, the preferred construction and embodiment being illustrated in the accompanying drawing, in which Fig. l is a diagrammatic view of a circuit controlled by a switch with this pilot light connected in shunt across the terminals of the switch;

Fig. 2 is a side elevationlof a switch with parts brokenaway for clearness and a panel plate therefor;

Fig. 3 is a face view of a switch block of this type with the face plate removed; and

Fig. 4 is a view of a pilot lamp of the type contemplated, showing the filament terminals in section.

It is frequently desirable to provide a visible indicationof whether a switch is open or closed; the simplest form for the application of a switch pilot light may be for the purpose of indicating the location of the switch itself in the dark. Another obvious use for an installation of this kind is in the provision of a pilot lamp in connection with a switch for controlling a load at a distance, the lighting of the pilot lamp indicating that the load is not connected, as well as the position of'the switch. A pilot lamp of this kind is highly desirable in any location normally in the dark where it is desirable to 55 indicate the location of the switch, as for controlling a larger illuminating light or installation.

This invention is particularly described in connection with. an electric lamp as indicated in Fig. 4, ofv the gas filled or neon type, having filameans 6 and l with corresponding terminals 8 5 and 9 which are spaced apart, the filaments being connected to a screw shell in. and end contact II respectively, and theterminals being spaced apart so that when cold the lamp has' a very high, if not an infinite, resistance but has a 10 definite flash point at which an applied voltage will cause a current pass between the terminals so that they will glow brightly. The present invention is not intended to cover specifically a lamp of this type as it is commercially available 15 for various flash voltages, it has a very low current consumption, and being of the filamentless type,-it has long life and service.

As shown in Fig. 1, a lamp l2 of this type is connected by conductors l3 and II to the ter- 20 minals l5 and I6 of a switch l1, which controls an electrical load indicated as l8 which has a lamp I2 is connected by its conductors l3 and ll 30 in series with the load through its conductors I9, 20 and 2i. This will cause the lamp l2 to gloyv brightly, indicating that the switch I! is open. When the switch is closed the terminals of the lamp I2 are short-circuited, no current 35 fiows through the lamp, and the load l8 receives its normal operating current in the proper manner. .The resistance of the lamp I2 is so high that no appreciable current fiows through the load It and-the wattage required by this lamp is so small as to be practically negligible even if the lamp is kept illuminated practically continuously.

In an actual installation of the pilot lamp, it is incorporated in connection with or as a part of a switch block 25, usually formed of porcelain or other insulating material, having screw terminals l5 and ii for conductors 2| and 20 joined by it and having a supporting metal strap 26 secured to the block 25 with eyelets 21 at the ends by 7 means of which it secures the block in an electric conduit box (not shown) and having threaded perforations 28 to which an apertured face plate 29 is secured by screws 30. Pivotally mounted in the-strap 26 and extending through an opening in the face plate is a switch tumbler 3i whlchismoved oppositely in a well known man-.

This socket provides for the attachment of a' conductor 34 extending from the end terminal I I of the lamp to one of the terminal screws l5 of the insulating block and a fastening clip 35 extends to the interior of the socket for providing a connection with the threaded shellill of the lamp which is connected by a conductor 36 with the otherscr'ew terminal it of the switch plug.

Thus it is seen that a new switch plug having the additional socket 32 may simply be substituted for the ordinary switch plug of the present control switch and a new apertured face plate, as 29, may, be substituted for the ordinary type of face plate without such perforation as now commonly employed, without materially changing the lighting equipment or installation. With this construction it is apparent that the switch and pilot light is an integral unit. When the switch which it shunts is opened the terminals of the pilot lamp will have nearly the same impressed voltage as the electrical energy of the source, ir- I respective of the resistance of the load, the load and switch l2 then being in series which will cause the pilot light to glow brightly. As soon as the switch is closed the terminals of the pilot light will be short-circuited and the light will be extinguished.

It is obvious that this pilot lamp may be used in a great variety of installations where it is desirable to indicate whether a circuit controllinga load is in operative connection or not.

I claim: I

1. As a unitary self-contained structure, a

, switch for controlling an electric circuit, said switch embodying an insulating supporting block, circuit terminals supported by the block, a switch mounted upon said block and included in the circuit with said terminals, a lamp socket integral with said block, a shunt circuit around said switch and in which shunt circuit said socket and said terminals are included, a lamp in said socket, said switch being operable to make and break connection between said terminals, said shunt circuit being rendered active when the first said circuit is interrupted by the switch, and rendered inactive when the first said circuit is closed by the switch, in combination with a wall plate having an opening, through which the switch lamp in said socket, said switch element being operable to make and break connection between said terminals, said shunt circuit being rendered active when the first said circuit is interrupted by the switch element, and rendered inactive when the first said circuit is closed by theswitch element, in combination with a wall plate having an opening through which a switch operating handle projects and also a second opening through which said lamp is visible, all of said parts being disposed within the confines of the peripheral edge of said wall plate.

3. As a. unitary selficontained article of manufacture, an insulating supporting block, a switch device mounted upon said block, a lamp socket integral with said block, a pair of terminals for a service line controlled by saidswitch device, a shunt circuit for said socket around said switch, said terminals being common to said service line and said shunt circuit, said switch being operable to cause said service line and said shunt circuit to be rendered active and inactive in opposition to each other, and means whereby a wall or face plate may be detachably secured to said supporting block.

CLARENCE H. KEHM. 

